1. Field of the Invention
This invention pertains to railway cars, and more specifically relates to a unitary roof for a railway car, and the method of its manufacture.
2. Description of Prior Art
During the many years that railway cars, and particularly box cars, have been manufactured, many of the details and practices during manufacture have undergone very little change. In the case of box car roofs, many of the prior art roofs are made from a plurality of separate roof panels, a number of which are required to span the length of the railway car and are welded or riveted together and to the upper surfaces of the side and end walls of the car to form the completed roof.
Eary U.S. Patents disclosing these general concepts are Jennings No. 696,976 which issued on Apr. 8, 1902; Russell No. 1,186,841 which issued on June 13, 1916; Small No. 1,681,813 which issued on Aug. 28, 1928; and Bonsoll No. 2,034,378 which issued on May 17, 1936. In each of these patents, a series of roofing panels transversely span a railway car and must be rigidly interconnected to each other and to the car frame. In the Bonsall patent, the roof panels are welded together, and in the earlier patents the panels are riveted or crimped together.
The welded type of car roof is not predominant and further development of this type of roof may be seen in patents such as Shaver No. 2,519,079 which issued on Aug. 15, 1950; Cisco No. 3,263,379 which issued on Aug. 2, 1966; and Allen et al No. 3,403,779 which issued on Nov. 5, 1968. In the Shaver patent the roof is fabricated at a location away from the car to form a unitary roof structure which can then be installed in completed, or nearly completed condition on the car. Shaver employs transverse panels in conjunction with other framing members, and the main advantage is that the roof is more easily assessible for the welding operations when it is assembled off the car.
A common feature in the above listed patents is that each roof comprises a series of similar panels which must not only be fastened to the upper side plates and end plates of the railway car walls, but must also be laboriously fastened to each other. It is apparent that a roof system which will shorten the installation time and reduce the amount of labor required will have a marked commercial advantage; the present invention provides this, or other advantages over other ordinary railway car roofing systems.